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What is energy?

What is energy?. The ability to do work Any object that has energy has the ability to create force. Measured in Joules like work because energy is stored as work. 3 Examples of Work: A moving ball has energy because it can create forces on whatever tries to stop it or slow it down.

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What is energy?

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  1. What is energy?

  2. The ability to do work Any object that has energy has the ability to create force. Measured in Joules like work because energy is stored as work. 3 Examples of Work: A moving ball has energy because it can create forces on whatever tries to stop it or slow it down. A sled at the top of a hill has energy because it can go down the hill and produce forces as it goes. The moving wind has energy because it can create forces on any object in its path. Definition

  3. Lets see what this chapter is about.

  4. POTENTIAL ENERGY Stored energy capable of being active

  5. Formula P. ENERGY = Mass x Gravity x Height 2 Joules = Kg x 9.8 m/s x Meters

  6. Lets Practice • You need to put a 1-kilogram mass that is on the floor, away on a shelf that is 3 meters high. How much energy does this use? • Solution: (1) You are asked for the potential energy. (2) You know the mass and height. (3) The equation for potential energy is Ep = m x g x h. (4) The equation is already in the right form. (5) Plug in numbers. Remember: Ep = (1 kg) x (9.8 m/sec2) x (3 m) = 29.4 joules

  7. KINETIC ENERGY Energy in motion that depends on mass and speed.

  8. Formula 2 K. ENERGY = 1/2 x Mass x Velocity Joules = 1/2 x Kg x m/sec

  9. Lets Practice • What is the kinetic energy required to move a 5 kg ball at a velocity of 10 m/s2. • You are solving for Kinetic Energy so the formula is KE = ½ mass x velocity2. • You know mass is 5 kg and velocity is 10 m/s2. • Plug them in – ½ (5 kg) (10m/s2)2. • Using your calculator to solve. • Answer – 250 J

  10. LAW OF CONSERVATION OF ENERGY Energy can never be created or destroyed, just transformed from one form to another.

  11. Ball Tossing Example • When you throw a ball in the air, its energy transforms from kinetic to potential and back to kinetic. • At any moment in its flight, the ball has exactly the same energy it had at the start. • The energy is divided between potential and kinetic, but the total is unchanged.

  12. The following diagram shows a cart rolling along a hilly road. Ignore the effect of friction. Arrange the five locations in order of increasing potential and kinetic energy. P → K ____, _____, _____, _____, _____ K→ P ____, _____, _____, _____, _____ Roller Coaster A D C B E

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